Known as a Flavivirus, the West Nile virus was first identified in 1937 in Africa and first found in North America in 1999. Migratory birds are considered the primary means whereby infection is spread within and between countries. The virus is transmitted by mosquitoes that have acquired infection by feeding on viremic birds. The virus is then amplified during periods of adult mosquito blood-feeding. Infected mosquitos then transmit the virus to humans and animals upon feeding thereon.
West Nile virus is the causative agent for West Nile Virus disease, particularly West Nile encephalitis, predominately in humans, other mammals and birds. The chief concern in both the United States and foreign countries is the lack of effective treatment for West Nile virus disease. Anti-inflammatory drugs are used to combat swelling of central nervous system tissues, but beyond that no medical intervention is available. Nor is there believed to be a suitable vaccine known to prevent the infection. To date, preventing contact with carriers appears to be the only means of controlling the West Nile virus.
What is therefore needed in the art is to provide a safe and effective equine West Nile virus vaccine composition. The vaccine composition should be sufficiently safened so as to be suitable for administration even to pregnant mares without adverse effect.
Also needed is a method for the prevention or amelioration of West Nile Virus disease, particularly West Nile encephalitis, in equidae and other mammals.